Micrometrically adjustable boring tool



Jan. 9, 1951 c. F. LE MAY 2,537,274

MICROMETRICALLY ADJUSTABLE BORING TOOL Filed June 5, 1948 IN VEN TOR.

Carl FLem BY @aan @nlm/'JY Patented Jan. 9, 1951 Detroit,Mich., assignorVto '"Ex'- Detroit, Mich., a; corpora- Y Carl'AF, Lell/Iay,

Cell- Corporation, tion` of Michiganl Application-June 5, 1948,.Seral N0,131,283

Y 1 Claim?Y The present inventionY pertains generally'. to devices foruse in machine tools andrnore speci'` callyy to a novel form ofadjustable boring tool; One object of-'the'invention istoiprovideaprecisely adju-stable boring; tool' of extremely" simple, sturdyconstruction and whichv will lend itself readily to economicalmanufacture;

Anotherobject is to provde=a boringytooT-of* the foregoing characterwhich will besusceptiblev of'veasy `adjustmentandyet capable of beingrigidly vlocked once a desiredlcondition of 'adjusti-l ment" has 'beenreached.`

Other 'objects andadvantages of the invention will vbecome apparent asthe'following detailed description'l proceeds, takend in the light ofthe accompanying drawings, inf-which: 1 Figurel is lan-enlargedfragmentary planviewof anm illustrative; boring tool embodying theVpresent invention.

Fig. 2 isa view=similar to Fig. 1 but with a portion of the boring barbroken away to show internal details of thetool."

Figs/f3 ist. ani-elevation of.theirtoolz-.sh'owirin aFig'.

2 and taken in the plane of the` line 3 3, .the

adjusting screw-fand Ytool bit being omitted.

Fig. 4 is a broken sectional view taken transverselytlrough the tool ofIthe line -4-4.-

Fig. `5 is'aside-view-vof-the graduated-adjusting screw.

Figf' is an end view of the adjusting screw shown in Fig. 5..

Fig. 7 is a sideelevation of the tool bit shown in Figs. 1, 2 and 4.

Fig. 8 is a plan view of the tool bit of Fig. 7.

While the invention is susceptible of various modifications andalternative constructions, a preferred embodiment has been shown in thedrawings and will be described below in considerable detail. It shouldbe understood, however, that there is no intention to limit theinvention to the specific form disclosed, but on the contrary, theintention is to cover all modifications and alternative constructionsfalling within the spirit and scope of the invention as expressed in theappended claim.

Upon more specific reference to the drawings, it will be perceived thatthe invention is there exemplified in the form of a boring tooldesignated generally by the reference numeral IU. The tool I0 comprisesa boring bar II which supports a tool bit I 2 together with a suitableadjusting screw I 4 for extending orV retracting the former. The toolbit I2 may be ground to any appropriate contour for a particular boringof Fig-2 and in the-'planel operation and in' the present instance isy'provided with'a hardened cutting tip I5 of carbide or the like. Theboring bar I I may, be supported at one or both ends in well known inthe art As shown in the drawing, the boring bar II`in al manner thisinstance is of substantially cylindrical cross section andis preferablyformed from a length`V of round stock. For slidably` supportingthetoolfy bit I2, the bar II is fashioned withV a generally transversepassageway I6 having a longitudinal axisl disposed-in skewed relation tothat Aof the boring bar II.

cross section, the Vpassageway i6 is formed-with a similar but slightlylarger cross section-sofas'At to create a comfortable sliding t withrespect to" the bit I2.

To render the tool bit'I2 axially adjustable with respect to thescrew I4in response to rota`- I 2-is provided with a` tion of the same, th'e'bitrelatively deep longitudinal bore I8. is formed with internal micrometerThe'latter' screw I4. Although the borev preferably terminates short ofthat portionof the tool bit -I2 whichnormally includes the-planeI ofmaximum stress when the tool is in an operative condition. Thus there isno appreciable weakening of the tool bit I2 since it will havesubstantially a full cross section of stock available to withstand theshear stress imposed along the above plane during a boring operation.Moreover, the use of the bore I8 results in a signiiicant saving in theamount of high grade steel used in the tool bit.

Provision is made for mounting the adjusting screw I4 and the tool bitI2 within the boring bar II so as to preclude longitudinal movement ofthe screw It while at the same time permitting the latter to be rotated.Furthermore, this is accomplished in an extremely simple manner andwithout the use of additional parts by taking advantage of the skewedrelation between the longitudinal axes of the passageway I6 and theboring bar II. Referring more particularly to Figs. 2 and 3, it will beobserved that a recess I9 is milled or otherwise cutinto the boring barIl adjacent one end of the skewed transverse passageway I5 so as to denea dat 28 which lies substantially perpendicular to the axis of thepassageway IB. Also defined by the recess I9 adjacent the innermost endof the same is an arof course;

Since "the tool bitA in the illustrative boring tool is of generallyrectangular threads of appropriate size to mesh neatly with acorresponding micrometer threads on the' adjusting I8 extendsalongasubstantial portion of the tool bit, the'former 1 cuate crescent-shapedslot 2| having its innermost lateral wall coplanar with the bottom ofsuch recess. The slot 2l is of appropriate width to receive thecylindrical flanged head 22 of the adjusting screw I4. With thisarrangement, the screw I4 by itself may be freely inserted and removedfrom the passageway I5 and by the same token its flange 22 may easily beinserted and removed from the slot 2l. When, however, the tool bit I2 isinserted into the opposite end of the passageway I6 and drawn up intooperating position by threaded engagement with the screw I4', the ange22 of the latter becomes Securely engaged by the slot 2 I. Under thesecircumstances, axial movement ofthe screw I4 will be precluded by theslot 2l and rotation of the screw I4 will thus result in extending orretracting the tool bit I2 along the axis of the passageway I6. Tofacilitate turning of the screw I4, the latter may be formed with a boss24 at its outer end, the boss, in turn, being provided with a polygonalrecess 25 which is engageable by any appropriate wrench.

While the construction just described is fully operative, there mustinevitably be a slight amount of backlash or lost motion in the screwthreads and also between the flange 22 and the side walls of the slot2l. Theoretically this lost motion, when once taken up by an initialadjustrnent, will have no further effect upon the positioning of thetool bit I2 as long as adjustments are made by rotating the screw I4 inthe same direction. This is due to the fact that micrometer type screwthreads have a selflocking characteristic. For precision boringoperations, however, suitable means must be provided to guard againstinaccuracies induced by vibration of the parts or due to some otheroperating condition. Thus the boring bar I I is equipped with one ormore locking screws 26 which threadedly engage tapped holes runningsubstantially perpendicular to the passageway IE and intersectingtherewith. The screws 25, like the adjusting screw I4, may havepolygonal recesses 28 to enable them to be tightened snugly against thetool bit I2 after the latter has been adjusted to a desired position.

For the purpose of facilitating the adjustment of the tool bit I2, theflange 22 of the screw I4 may be calibrated to allow for the angularityof its movement with respect to the axis of the boring bar II. Thus theperiphery of the flange 22 may be provided with a series of graduations2S arranged to read, for example, in tens of thousandths of an inch. Areference mark 3) is also provided on the flat 2i) of the boring bar foruse with the graduations 29 on the adjusting screw flange.

In the light of the foregoing, it will be appreciated that there hasbeen provided a boring tool of extremely simple and economicalconstruction. Furthermore, by reason of its novel arrangement, the toolis sturdy and reliable and capable of use in boring operations requiringa high degree of precision.

I claim as my invention:

In a boring tool, the combination of a boring bar having a, generallyrectangular passageway running transversely thereof, said boring baralso having adjacent one end of the passageway a recess including acrescent-shaped slot, the innermost lateral wall of said slot beingcoplanar with the bottom of the recess, an axially slidable tool bit ofrectangular cross section housed within the passageway of said boringbar, said tool bit having a coaxial threaded bore running longitudinallythereof, an adjusting screw adapted to threadedly engage said tool bitfor adjustment of the same axially of the passageway of said boring bar,and a head of general cylindrical shape integral with said adjustingscrew and having peripheral graduations thereon to facilitate adjustmentof said tool bit, said head being engageable on one end by the bottom ofsaid recess and said innermost lateral wall of said slot, said head alsobeing engageable on the opposite end by the other lateral wall of saidcrescent-shaped slot.

CARL F. LE MAY.

REFERENCES CITED The following references are of record ln the file ofthis patent:

UNITED STATES PATENTS Number 4 Name Date 2,096,489 Hassig Oct. 19, 19372,274,007 Smith Feb. 24, 1942

